It's difficult when behind a Till etc. when shoppers get nasty. This isn't about you, however it's difficult to take abuse during your working day.
Frustration and fear cause some to become angry. Where is your supervisor in this? Is there a store security officer, in 1 store locally, he is hopeless - preferring to chat about his marital problems
Let us know how you get on and do speak to your Store Manager. Abuse isn't acceptable!